1. Field of the Invention
The present invention relates to a duplex scanning apparatus, and more particularly to a duplex scanning apparatus with an elastic pressing member disposed between two scan positions, for enhancing the overall scan quality.
2. Related Art
In a conventional duplex scanning apparatus using either a charge-coupled device (CCD) type image sensor scanning module or a contact type image sensor (CIS) scanning module, two transparent glass sheets for the purposes of defining a scan region and a passageway and separating a paper sheet from the scanning module have to be disposed on the paper transporting path. Even if the passageway is configured to have an adjustable clearance, it still has to maintain certain space to allow original sheets to pass through smoothly without paper jam occurrence. Since the original sheets to be scanned have various thicknesses, the sheet passageway cannot be configured to be too narrow, or otherwise the thicker original sheets, such as a business card, a magnetic card, a chip card and etc, cannot enter and pass the scan region smoothly. For a thin sheet, such as a receipt, letter, and etc., however, the movement of the thin sheet produces vertical deflections if the sheet passageway is configured to be wide. More particularly, when the CIS scanning module is adopted, image distortion will occur due to any unevenness or curling of the document sheet.